Aerial Shell Drift Effects

K.L. and B.J Kosanke

ABSTRACT: A prime consideration in determining separation distance requirements for aerial fireworks displays is where fallout of dangerous debris is likely to occur. Certainly the most dangerous single piece of fallout is a dud aerial shell. Thus it is important to have knowledge of where duds may fall during typical displays. This would be a relatively simple situation if aerial shells were ballistically stable, and they precisely followed the path determined by mortar orientation, shell muzzle velocity, and atmospheric conditions. Unfortunately, however, aerial shells tend to drift from their ideal (predicted) path, and that drift is greater than most realize. In order to determine where dud shells fall, a large number of aerial shells, both spherical and cylindrical, were fired into the air after having been rendered incapable of bursting at altitude. Most firings were from mortars that were positioned vertically and under calm wind conditions; however, some firings were from angled mortars. For spherical aerial shells, 7.6 cm to 25.4 cm (3 in. to 10 in.) it was found that, on average, duds fall 3.8 m per cm (32 ft per in.) of shell size, from the point ballistically predicted. Further the data suggests that drifts as great as 12 m per cm (100 ft per in.) of shell size may occur nearly 1 percent of the time. For cylindrical shells, 7.6 cm to 15.2 cm (3 in. to 6 in.) it was found that, on average, duds fall 2.4 m per cm (20 ft per in.) of shell size, from the point ballistically predicted. Finally, a large number of 10.2-cm (4-in.) cylindrical shells were fired in order to determine the effect of shell weight, shell length, and lift powder weight on drift distance.


Ref: Selected Pyrotechnic Publication of K.L. and B.J Kosanke, Part 2, (1990-1992), pp 67-79
(K2_67)


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